Journeyman Electrician Exam (NEC)Special Occupancies, Equipment, and ConditionsMedium
A client is installing a new solar photovoltaic (PV) system on a commercial building. The PV array has a maximum system voltage of 500V. What is the minimum size of the equipment grounding conductor (EGC) for a PV circuit with 40A overcurrent protection, using copper conductors?
- A4 AWG copper
- B10 AWG copper
- C8 AWG copper
- D6 AWG copper
Show answer & explanationAnswer & explanation
Correct answer: B. 10 AWG copper
According to NEC Table 250.122, for a circuit protected by a 40A overcurrent device, the minimum size copper equipment grounding conductor is 10 AWG. This table applies to PV systems as well, unless specific PV articles require otherwise, which is not the case for EGC sizing based on OCPD.
Why the other options are wrong
- A. 4 AWG copper is for OCPDs up to 200A.
- C. 8 AWG copper is for OCPDs up to 60A.
- D. 6 AWG copper is for OCPDs up to 100A.
PV EGC Sizing (NEC)
The minimum size of the equipment grounding conductor (EGC) for PV circuits is determined by the rating of the overcurrent protective device (OCPD) in accordance with NEC Table 250.122.
- Based on the OCPD rating, not the circuit current.
- NEC Table 250.122 is the primary reference.
- Ensures fault current path for safety.
Memory trick: EGC: Match the BREAKER, not the wire.